The present invention relates to gripping assemblies for securement of sheet material, such as plastic sheeting, on structural components wherein the sheet material is secured in channel portions of structural components or members.
The sheet material is secured in the channel in structural members by a gripper member against disengagement of the sheet by forces tending to disengage the material.
The present invention is herein described in relation to its utilization in greenhouse structures, typically involving a structure comprising structural members, pipes, etc., certain of which may be generally vertical and other components disposed at horizontal or inclined orientation. In greenhouse structures and the like, sheet material may typically be transparent for transmission of sunlight and daylight for plant culture, and the sheet material may typically extend between structural components to provide weather and wind shielding while providing for admission of sunlight and daylight.
It is necessary that disengagement of sheet material be prevented to the extent possible. Forces tending to disengage the sheet material typically include wind forces, thermal expansion of the sheet material which reduces tension stress in the material and tends to dislodge it, air pockets between gripping components, and thermal expansion of air pockets.
The present invention provides sheet material gripping assemblies comprising a gripping member inserted into opposed channel portions of an elongate structural member to secure the sheet material. The gripping member is of generally zigzag configuration and is adapted to engage in opposite channels defined in the elongate member. The gripping member is sufficiently resilient to enable manual deformation thereof in the process of engaging successive zigzag portions of the gripping member in the oppositely facing channels of the elongate member.
The gripping member is deformed along successive lengths thereof during the manual insertion process, as indicated in FIG. 4 of the drawings, thus to engage successive zigzag portions thereof into the opposing channels. The spring clamping forces between the gripping member and the opposed channels resist and prevent disengagement of the sheet material from the structural member.